Exhaust control valve branch communication and wastegate

ABSTRACT

Methods and systems for adjusting a branch communication and wastegate valve in a dual scroll turbocharger system are provided. In one example, a method may include adjusting the branch communication and wastegate valve in a passage connecting a first scroll, a second scroll, and a wastegate passage may control an amount of exhaust flow to a turbine during certain engine operating conditions.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication No. 62/104,565, “EXHAUST CONTROL VALVE BRANCH COMMUNICATIONAND WASTEGATE,” filed on Jan. 16, 2015, the entire contents of which arehereby incorporated by reference for all purposes.

FIELD

The present disclosure relates to a turbocharger of an engine.

BACKGROUND/SUMMARY

Twin, or dual, scroll turbocharger configurations may be used inturbocharged engines. A twin scroll turbocharger configuration mayseparate an inlet to a turbine into two separate passages connected toexhaust manifold runners. In this way, exhaust from the enginecylinders, whose exhaust gas pulses may interfere with each other, arefluidically separated.

For example, on an 14 engine with a cylinder firing order of exhaustmanifold runners 1-3-4-2, exhaust manifold runners 1 and 4 may beconnected to a first inlet of a twin scroll turbine and exhaust manifoldrunners 2 and 3 may be connected to a second inlet of said twin scrollturbine, where the second inlet is different and fluidically separatedfrom the first inlet. In this way, separating exhaust gas pulses mayresult in an increase in efficiency of exhaust gas delivery to a turbinein some cases.

However, under some engine operating conditions, separating exhaust gaspulses as described above may reduce an efficiency of exhaust gasdelivery to a turbine. For example, under certain engine operatingconditions, e.g., high speed and high load conditions, separatingexhaust gas pulses may result in an increase in backpressure and pumpingwork. This increase in backpressure and pumping work may be due to morerestrictive, lower volume passages between the exhaust and the turbinein a dual scroll turbine, as compared to a passage that is not separatedin a single scroll turbine. As such, the amount of exhaust gas in thecylinder may raise the pressure in the lower volume passages compared tothe relatively larger volume, unseparated passage. The increasedbackpressure may also result in higher levels of hot residual gas in thecylinder, and may reduce the engine's output power.

One example approach for reducing backpressure and pumping work in atwin scroll turbocharger has been shown by Styles et al. in US2014/0219849. Herein, systems positioning a branch communication valvebetween a first scroll and a second scroll in a twin (e.g., dual) scrollturbocharger system is provided. In an example, a branch communicationvalve may be positioned adjacent to a dividing wall separating a firstscroll and a second scroll of the twin turbocharger. In an openposition, the branch communication valve may increase fluidcommunication between the first scroll and the second scroll, and in aclosed position, the branch communication valve may decrease fluidcommunication between the first scroll and the second scroll. In someexamples, each scroll may include a corresponding wastegate and acorresponding wastegate valve to control the amount of exhaust gas whichpasses through turbine.

The inventors herein have recognized a potential issue with the exampleapproach of Styles et al. For example, there may be cost, weight, andpackaging penalties associated with including both a branchcommunication valve and one or more wastegate valves in the turbochargerand engine system. Further, there may also be an additional burden on anengine control and monitoring system when two or more valves areimplemented and adjusted by the aforementioned system based on engineoperating conditions.

The inventors herein have identified an approach to at least partlyaddress the above issue. In one example approach, a method may beprovided, comprising adjusting a valve positioned in a passageconnecting a first scroll and a second scroll of a turbine to increasean amount of exhaust flow to the turbine when a turbine speed is lessthan a threshold and during a first load condition, and adjusting thevalve to decrease the amount of exhaust flow to the turbine when turbinespeed is greater than the threshold, and during a second load condition.In this example, the valve is in fluid communication with a wastegatepassage flowing exhaust around the turbine. In this way, an amount offluidic communication and conveyance between the first scroll and thesecond scroll, and to the wastegate passage, may be adjusted to providedesired boost pressure based on various engine operating conditions.

For example, the first load condition may include one or more of boostpressure being less than a desired boost pressure, engine load beinggreater than a threshold load, and torque demand increasing. On theother hand, in another example, the second load condition may includeone or more of boost pressure being greater than a desired boostpressure, engine load being less than a threshold load, and torquedemand decreasing. By adjusting the single valve, such as a combinedbranch communication and wastegate valve, to control boost pressureresponsive to various engine operating conditions, backpressure andpumping work may also be reduced. Further, additional burden on anengine control and monitoring system may be reduced when the singlevalve is implemented and adjusted as compared to implementing separatebranch communication and wastegate valves.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of a first example engine including adual (twin) scroll turbocharger and a branch communication and wastegatevalve.

FIG. 2 shows a schematic diagram of a second example engine including adual (twin) scroll turbocharger and a branch communication and wastegatevalve.

FIGS. 3A-3D show sectional views of an example branch communication andwastegate valve in four example positions or states.

FIGS. 4A-4D show sectional views of another example branch communicationand wastegate valve in four example positions or states.

FIG. 5 shows an example method for adjusting a branch communication andwastegate valve.

FIG. 6 shows an example operation plot for adjusting a branchcommunication and wastegate valve responsive to engine operatingconditions.

DETAILED DESCRIPTION

The following description relates to systems and methods for controllingfluid communication between a first and second scroll in a dual (i.e.twin) scroll turbocharger system having a branch communication andwastegate valve in an engine system, such as the engine systems in FIGS.1-2. As shown in FIGS. 3A-4D, in some embodiments, a combined, dual,and/or integrated functionality valve, such as a single branchcommunication and wastegate valve, may be provided to control anincrease or decrease in fluid communication between the first and secondscrolls, and exhaust gas flow through the turbine and wastegate. Thecombined branch communication and wastegate valve may be a cylindricalvalve, as shown in FIGS. 3A-3D, or a spool valve, as shown in FIGS.4A-4D, or any combination thereof. Opening the branch communication andwastegate valve may allow increased fluid communication between thefirst and second scrolls, while closing the branch communication andwastegate valve may reduce fluid communication between the first andsecond scrolls. Thus, an amount of fluidic communication and conveyancebetween the first scroll and the second scroll may be adjusted based onengine operating conditions, as shown below in reference to FIG. 5.Example valve adjustments based on engine operating conditions are shownin FIG. 6.

Turning now to FIG. 1, a schematic diagram of an engine 10, which may beincluded in a propulsion system of a vehicle, is shown. Engine 10 may becontrolled at least partially by a control system including controller12 and by input from a vehicle operator 14 via an input device 16.Controller 12 may be a microcomputer, including a microprocessor unit,input/output ports, an electronic storage medium for executable programsand calibration values, random access memory, keep alive memory, and adata bus. As depicted, controller 12 may receive input from a pluralityof sensors (not shown), which may include user inputs and/or sensors(such as transmission gear position, gas pedal input, exhaust manifoldtemperature, air-fuel ratio, vehicle speed, engine speed, mass airflowthrough the engine, boost pressure, ambient temperature, ambienthumidity, intake air temperature, cooling system sensors, and others).The controller may also send a plurality of control signals to variousengine actuators (not shown) in order to adjust engine operation basedon signals received from the sensors (not shown). In this example, inputdevice 16 includes an accelerator pedal and a pedal position sensor 18for generating a proportional pedal position signal PP. Engine 10 may beincluded in a vehicle such as a road vehicle, among other types ofvehicles. While the example applications of engine 10 will be describedwith reference to a vehicle, it should be appreciated that various typesof engines and vehicle propulsion systems may be used, includingpassenger cars, trucks, etc. Engine 10 may include a plurality ofcombustion chambers (i.e., cylinders). In the examples shown in FIGS.1-2, engine 10 may include combustion chambers 20, 22, 24, and 26,arranged in an inline four configuration. It should be understood,however, that though FIG. 1 shows four cylinders, engine 10 may includeany number of cylinders. For example, engine 10 may include any suitablenumber of cylinders, e.g., 2, 3, 4, 5, 6, 8, 10, 12, or more cylindersin any configuration, e.g., V-6, I-6, V-12, opposed 4, etc. Though notshown in FIGS. 1-2, each combustion chamber (i.e. cylinder) of engine 10may include combustion chamber walls with a piston positioned therein.The pistons may be coupled to a crankshaft so that reciprocating motionsof the pistons are translated into rotational motion of the crankshaft.The crankshaft may be coupled to at least one drive wheel of a vehiclevia an intermediate transmission system, for example. Further, a startermotor may be coupled to the crankshaft via a flywheel to enable astarting operation of engine 10.

Each combustion chamber may receive intake air from an intake manifold28 via an air intake passage 30. Intake manifold 28 may be coupled tothe combustion chambers via intake ports. For example, in FIG. 1, intakemanifold 28 is shown coupled to cylinders 20, 22, 24, and 26 via intakeports 32, 34, 36, and 38, respectively. Each respective intake port maysupply air and/or fuel to the respective cylinder for combustion.

Each combustion chamber may exhaust combustion gases via an exhaust portcoupled thereto. For example, exhaust ports 40, 42, 44 and 46, are shownin FIG. 1 coupled to cylinders 20, 22, 24, 26, respectively. Eachrespective exhaust port may direct exhaust combustion gases from arespective cylinder to an exhaust manifold or exhaust passage.

Each cylinder intake port can selectively communicate with the cylindervia an intake valve. For example, cylinders 20, 22, 24, and 26 are shownin FIG. 1 with intake valves 48, 50, 52, and 54, respectively. Likewise,each cylinder exhaust port can selectively communicate with the cylindervia an exhaust valve. For example, cylinders 20, 22, 24, and 26 areshown in FIG. 1 with exhaust valves 56, 58, 60, and 62, respectively. Insome examples, each combustion chamber may include two or more intakevalves and/or two or more exhaust valves.

Though not shown in FIGS. 1-2, in some examples, each intake and exhaustvalve may be operated by an intake cam and an exhaust cam, respectively.Alternatively, one or more of the intake and exhaust valves may beoperated by an electromechanically controlled valve coil and armatureassembly (not shown). The position of an intake cam may be determined byan intake cam sensor (not shown). The position of exhaust cam may bedetermined by an exhaust cam sensor (not shown).

Intake passage 30 may include a throttle 64 having a throttle plate 66.In one example, a position of throttle plate 66 may be varied bycontroller 12 via a signal provided to an electric motor or actuatorincluded with throttle 64, a configuration that is commonly referred toas electronic throttle control (ETC). In this manner, throttle 64 may beoperated to vary the intake air provided to the combustion chambers. Theposition of throttle plate 66 may be provided to controller 12 bythrottle position signal TP from a throttle position sensor 68. Intakepassage 30 may include a mass air flow sensor 70 and a manifold airpressure sensor 72 for providing respective signals MAF and MAP tocontroller 12. MAP and MAF may not both be present, and only one sensormay be used.

In FIGS. 1-2, fuel injectors are shown coupled directly to thecombustion chambers for injecting fuel directly therein in proportion toa pulse width of a signal FPW received from controller 12 via anelectronic driver, for example. For example, fuel injectors 74, 76, 78,and 80 are shown in FIG. 1 coupled to cylinders 20, 22, 24, and 26,respectively. In this manner, the fuel injectors provide what is knownas direct injection of fuel into the combustion chamber. Each respectivefuel injector may be mounted in the side of the respective combustionchamber or on the top of the respective combustion chamber, for example.In other examples, one or more fuel injectors may be arranged in the airintake manifold 28 in a configuration that provides what is known asport injection of fuel into the intake ports (e.g., intake ports 32, 34,36, and 38) upstream of combustion chambers. Though not shown in FIG. 1,fuel injectors may be configured to deliver fuel received via a highpressure fuel pump (not shown) and a fuel rail (not shown).Alternatively, fuel may be delivered by a single stage fuel pump atlower pressure, in which case the timing of the direct fuel injectionmay be more limited during the compression stroke than if a highpressure fuel system is used. Further, the fuel tank may have a pressuretransducer providing a signal to controller 12. In some examples, fuelmay be injected directly into each respective combustion chamber. Thismay be referred to as direct injection. Indirect injection may be usedin other examples.

The combustion chambers of engine 10 may be operated in a compressionignition mode, with or without an ignition spark. In some examples, adistributorless ignition system (not shown) may provide an ignitionsparks to spark plugs coupled to the combustion chambers in response tocontroller 12. For example, spark plugs 82, 84, 86, and 88 are shown inFIG. 1 coupled to cylinders 20, 22, 24, and 26, respectively.

As mentioned above, intake passage 30 may communicate with one or morecylinders of engine 10. In some embodiments, one or more of the intakepassages may include a boosting device such as a turbocharger 90.Turbocharger 90 may be include a turbine 92 and a compressor 94 coupledon a common shaft 96. The blades of turbine 92 may be caused to rotateabout the common shaft 96 as a portion of the exhaust gas stream or flowdischarged from engine 10 impinges upon the blades of the turbine.Compressor 94 may be coupled to turbine 92 such that compressor 94 maybe actuated when the blades of turbine 92 are caused to rotate. Whenactuated, compressor 94 may then direct pressurized fresh gas to airintake passage 28 where it may then be directed to engine 10. The speedof the turbine may be inferred from one or more engine operatingconditions. In some examples, the rotational speed of the turbine 92 maybe measured with a sensor. For example a speed sensor 97 may be coupledwith common shaft 96. A signal indicative of the speed may be delivered,for example, to the controller 12.

Turbine 92 may include at least one wastegate to control an amount ofboost provided by said turbine. In a dual scroll system, both scrollsmay share a wastegate to control an amount of exhaust gas which passesthrough turbine 92. For example, in FIG. 1, the first scroll 100 andsecond scroll 102 include a wastegate passage 104. Exhaust flow throughwastegate passage 104 may be controlled by a valve, such as a valve 140discussed below, to regulate the amount of exhaust gas bypassing turbine92. In one embodiment, an area of an opening of the wastegate passage104 may be positioned equally open to each of the scrolls, such thatsubstantially similar amounts of exhaust gas flow may exit each of thescrolls into wastegate passage 104 during some conditions.

Engine 10 may employ a dual scroll (or twin scroll or two-pulse)turbocharger system 98 wherein at least two separate exhaust gas entrypaths flow into and through turbine 92. A dual scroll turbochargersystem may be configured to separate exhaust gas from cylinders whoseexhaust gas pulses interfere with each other when supplied to turbine92. For example, FIG. 1 shows a first scroll 100 and a second scroll102, wherein each of the first scroll and second scroll may be used tosupply separate exhaust flow to turbine 92. The cross-sectional shape offirst scroll 100 and second scroll 102 may be of various shapes,including circular, square, rectangular, D-shaped, etc.

For example, if a four-cylinder engine (e.g., an 14 engine such as shownin FIG. 1) has a firing sequence of 1-3-4-2 (e.g., cylinder 20 followedby cylinder 24 followed by cylinder 26 followed by cylinder 22), thencylinder 20 may be ending its expansion stroke and opening its exhaustvalves while cylinder 22 still has its exhaust valves open. In asingle-scroll or undivided exhaust manifold, the exhaust gas pressurepulse from cylinder 20 may interfere with the ability of cylinder 22 toexpel its exhaust gases. However, by using a dual scroll turbochargersystem, wherein exhaust ports 40 and 46 from cylinders 20 and 26 areconnected to one inlet of the first scroll 100, and exhaust ports 42 and44 from cylinders 22 and 24 are connected to the second scroll 102,exhaust pulses or gas flow may be separated, and pulse energy drivingthe turbine may be increased.

Exhaust gases exiting turbine 92 and/or a wastegate via wastegatepassage 104 may pass through an emission control device 112. Emissioncontrol device 112 can include multiple catalyst bricks, in one example.In another example, multiple emission control devices, each withmultiple bricks, can be used. In some examples, emission control device112 may be a three-way type catalyst. In other examples, emissioncontrol device 112 may include one or a plurality of a diesel oxidationcatalyst (DOC), selective catalytic reduction catalyst (SCR), and adiesel particulate filter (DPF). After passing through emission controldevice 112, exhaust gas may be directed to a tailpipe 114.

Engine 10 may include an exhaust gas recirculation (EGR) system 116. EGRsystem 116 may deliver a portion of exhaust gas exiting engine 10 intothe engine air intake passage 30. The EGR system includes an EGR conduit118 coupled to a conduit or exhaust passage 122, downstream of theturbine 92, and to the intake passage 30. In some examples, EGR conduit118 may include an EGR valve 120 configured to control an amount ofrecirculated exhaust gas. As shown in FIG. 1, EGR system 116 is a lowpressure EGR system, routing exhaust gas from downstream of the turbine92 to upstream of the compressor 94. In some examples, an EGR cooler(not shown) may be placed along EGR conduit 118 which may serve toreduce the temperature of the exhaust gas being re-circulated. Inanother example, a high pressure EGR system may be used in addition toor in place of the low pressure EGR system. As such, the high pressureEGR system may route exhaust gas from one or more of the first scroll100 and second scroll 102, upstream of the turbine 92, to the intakepassage 30, downstream of the compressor 34.

Under some conditions, EGR system 116 may be used to regulate thetemperature and or dilution of the air and fuel mixture within thecombustion chambers, thus providing a method of controlling the timingof ignition during some combustion modes. Further, during someconditions, a portion of combustion gases may be retained or trapped inthe combustion chamber by controlling exhaust valve timing.

In some examples, controller 12 may be a microcomputer, including amicroprocessor unit, input/output ports, an electronic storage mediumfor executable programs and calibration values, random access memory,keep alive memory, and a data bus. As depicted, controller 12 mayreceive input from a plurality of sensors, which may include user inputsand/or sensors (such as transmission gear position, gas pedal input,exhaust manifold temperature, air-fuel ratio, vehicle speed, enginespeed, mass airflow through the engine, ambient temperature, ambienthumidity, intake air temperature, cooling system sensors, and others).The controller may also send a plurality of control signals to variousengine actuators (not shown) in order to adjust engine operation basedon signals received from the sensors (not shown). In this example, inputdevice 16 includes an accelerator pedal and a pedal position sensor 18for generating a proportional pedal position signal PP. Further,controller 12 is shown in FIG. 1 receiving various signals from sensorscoupled to engine 10, in addition to those signals previously discussed,including: engine coolant temperature (ECT) from a temperature sensor128; an engine position sensor 130, e.g., a Hall effect sensor sensingcrankshaft position. Barometric pressure may also be sensed (sensor notshown) for processing by controller 12. In some examples, engineposition sensor 130 produces a predetermined number of equally spacedpulses every revolution of the crankshaft from which engine speed (RPM)can be determined. Additionally, various sensors may be employed todetermine turbocharger boost pressure. For example, a pressure sensor132 may be disposed in intake passage 30 downstream of compressor 94 todetermine boost pressure. Additionally, each scroll of the dual scrollsystem 98 may include various sensors for monitoring operatingconditions of the dual scroll system. For example, the first scroll 100may include an exhaust gas sensor 134 and the second scroll 102 mayinclude an exhaust gas sensor 136. Exhaust gas sensors 134 and 136 maybe any suitable sensor for providing an indication of exhaust gasair/fuel ratio such as a linear oxygen sensor or UEGO (universal orwide-range exhaust gas oxygen), a two-state oxygen sensor or EGO, a HEGO(heated EGO), a NOx, HC, or CO sensor. In some cases a single sensor maybe used to, for example, sense an air/fuel ratio. The single sensor maybe used in place of using sensors 134 and 136, and may be positioned,for example, downstream from the turbine in the conduit or exhaustpassage 122.

Each scroll may receive exhaust gas from a specific set of cylinder viaspecific exhaust manifold segments and distinct inlets. Exhaust gasesflowing through the first scroll 100 and exhaust gases flowing throughthe second scroll 102 are separated by a dividing wall 138. As discussedabove, separating exhaust gas flow (i.e. exhaust gas pulses) in thefirst and second scrolls may increase low-end engine torque and reduce aduration desired to achieve said torque. As a result, during certainconditions such as high engine load, separating the exhaust gas pulsesmay result in an increase in efficiency of exhaust gas flow delivery toa turbine. However, during some engine operating conditions, separatingexhaust gas pulses as described above may reduce the efficiency ofexhaust gas delivery to the turbine. For example, during high enginespeed, separating exhaust gas pulses as described above may increasebackpressure and pumping work due, in part, to a smaller, morerestrictive lower scroll volume between the exhaust valve and theturbine compared to a combined, unseparated single turbine inlet scroll.In other words, a volume of exhaust gas exiting the cylinder(s) mayraise the pressure more in the aforementioned dual scroll configuration,since the separated first scroll and second scroll may have a relativelysmaller volume as compared to a scroll configuration where the scrollsor passages are not separated. In response, engine power output may bereduced.

Increasing fluid communication and conveyance between the first andsecond scrolls during certain engine operating conditions, such as highspeed and/or high load, may allow increased engine efficiency and poweroutput. Thus, a passage 139 may fluidically bridge the first scroll 100and the second scroll 102, such that an amount of exhaust gas in thefirst scroll 100 may flow to the second scroll 102, and mix with anamount of exhaust gas in the second scroll 102. Likewise, an amount ofexhaust gas in the second scroll 102 may flow to the first scroll 100,and mix with an amount of exhaust gas in the second scroll 102. Further,a valve 140 may be provided within passage 139 positioned withindividing wall 138 to allow fluid communication and conveyance betweenthe first and second scroll during certain engine operating condition.In another example, the valve 140 may be disposed at an opening of thedividing wall. Moreover, the valve may be positionable or adjustable viaone or more signals received from controller 12 in a continuous mannerthrough selected positions or ranges, discussed below.

In one embodiment, valve 140 may be referred to as a combined branchcommunication valve and wastegate valve 140, or simply as valve 140. Assuch, the term “valve” as used herein may be understood to mean anobstruction, which may be movable or positionable to control a flow offluid, and may be understood to mean a movable obstruction, which may behoused in and/or coupled with various components such as a housing orbody, etc. As shown in the example embodiment illustrated in FIGS. 1-2,valve 140 may be positioned such that the valve bridges the first scroll100 and the second scroll 102. As such, in one example, opening valve140 may provide a passage to increase fluid communication and conveyancebetween the first and second scrolls of the turbine. Further, the valve140 may be opened a metered amount to each of the first and secondscrolls, such that fluid communication may be restricted to a desiredamount. In this way, only a portion of the amount of exhaust gas mayflow between the first and second scrolls. In another example, valve 140may be completely or fully opened such that there may be a larger amountof exhaust gas flow and fluid communication between the first and secondscrolls, compared to the portion of the amount of exhaust gas flow whenthe valve 140 is opened a metered amount.

In yet another example, closing the valve 140 may decrease fluidcommunication and conveyance between the first and second scrolls. Insome cases, the valve may be completely or fully closed such thatconsiderably no exhaust gas may communicate between the first and secondscrolls. In other words, substantially all exhaust gas flow within thefirst scroll and all exhaust flow within the second scroll may separateand independently directed to the turbine, such as turbine 92. As shownin FIGS. 1-2, embodiments of valve 140 described herein may be used inthe first scroll and/or the second scroll within the turbochargerhousing assembly and/or in the exhaust passages (e.g., first scroll 100and/or second scroll 102 leading to an inlet of the turbocharger).

Thus, the valve may be adjusted between selected positions. For example,valve 140 may be movable between four selected positions, as shown inreference to FIGS. 3A-4D. In this example, a first set of the selectedpositions may provide fluid communication and conveyance between thefirst scroll 100 and the second scroll 102. Moreover, a second set ofthe selected positions may provide fluid communication and conveyancebetween one or both of the first scroll 100 and second scroll 102 and apoint 106 downstream from turbine 92.

As a result, adjustments to a position of valve 140 may control arotational speed of the turbine 92, as described, and in turn, regulatethe speed of compressor 94. Thus, in some embodiments, only a singleelement, such as valve 140, may provide both control of exhaust gasthrough the wastegate passage 104, and controlled fluidic communicationand conveyance between two or more scrolls that may be present in engine10. Increasing fluid communication and conveyance may include allowingexhaust gas from the first scroll 100 and exhaust gas from the secondscroll 102 to mix and enter an opposite or other scroll(s). In oneexample, wastegate control may include allowing at least a portion ofexhaust gas from each of first scroll 100 and second scroll 102 to enterwastegate passage 104, thereby bypassing turbine 92. In other examples,wastegate control may include closing the wastegate to preventsubstantially all exhaust gas from the first and second scrolls (and/oradditional scroll(s)) from bypassing the turbine. Since the position ofvalve 140 may control the rotational speed of the turbine, in someexamples, the amount of opening of valve 140 (e.g., a metered orprescribed amount, or fully opened or fully closed) to each of the firstand second scrolls, and/or to the wastegate passage may be based on oneor more engine operating conditions, such as engine speed, engine load,desired or demanded torque, and/or increasing or decreasing torque.

Turning now to FIG. 2, another example embodiment of the dual scrollturbocharger system 98 is shown. Other arrangements not specificallyillustrated may also be possible in accordance with the presentdisclosure. Similar to FIG. 1, dual scroll turbocharger system 98 mayinclude first scroll 100 and second scroll 102. In one embodiment,second scroll 102 may be fluidically separated from first scroll 100 bythe dividing wall 138, and passage 139 may fluidically bridge the firstscroll 100 and the second scroll 102, such that an amount of exhaust gaswithin each of the first scroll 100 and the second scroll 102 may mixwith an amount of exhaust gas in the opposite scroll. In someembodiments, by adjusting valve 140 based on engine operatingconditions, the turbine may be operated in varying modes, and thedynamic range over which boost can be provided by the turbocharger isenhanced. In addition, the aforementioned arrangements may reduceweight, cost, and/or package penalties.

As shown in FIG. 2, valve 140 may be integrated into, or co-locatedwith, cylinder head 39 of engine 10 configured to use turbochargersystem 98. In another example, valve 140 may be integrated into, orco-located with, an exhaust manifold 41 of engine 10 configured to useturbocharger system 98. In another example, valve 140 may be integratedinto cylinder head 39 containing the integrated exhaust manifold 41.Alternatively, in yet another example, valve 140 may be integrated intoturbocharger 90 of engine 10 configured to use turbocharger system 98.Further, valve 140 may be integrated into a valve engagement piece (notshown) specifically used to hold valve 140 securely in place. In someembodiments, valve 140 may include a valve body. The valve 140 mayinclude one or more external surfaces to allow heat to dissipate fromthe valve body into a surrounding environment. Thus, thermal degradationof the valve may be reduced.

Now referring to FIGS. 3A-3D, sectional views of a first example branchcommunication and wastegate valve in four example positions or statesare shown. The first scroll 100, herein also termed the first passage,may be in front, behind, or above a second scroll 102, herein termed thesecond passage, as viewed from the plane of the paper. In oneembodiment, the sectional views may be viewed or perceived through acenter of a scroll, such as the first scroll 100. The other scroll,e.g., second scroll 102, may be in front or behind the plane of thesectional views.

As illustrated in FIGS. 3A-3D, valve 140 may be a cylindrical valve 140.In this embodiment, valve 140 may rotate on an axis 141 substantiallyperpendicular to a flow of exhaust gas (and as illustrated, the valvemay rotate perpendicular to the plane of the paper) within each of thefirst scroll 100 and the second scroll 102. Further, in this embodiment,valve 140 may include an element 147 that rotates on axis 141substantially perpendicular to the exhaust flow within each of the firstand second scrolls. In one example, cylindrical valve 140 may bepositioned at least in an area substantially adjacent to, and share atleast an interface with the first scroll 100 and the second scroll 102.In this way, valve 140 may provide selective fluidic communication andconveyance between one or more combinations of first scroll 100, secondscroll 102, and the wastegate passage 104 to point 106 (depicted abovein FIGS. 1-2) downstream from turbine 92.

In one embodiment, valve 140 may be adjusted and movable in a continuousmanner through selected ranges, positions, or states, as described indetail in FIGS. 3A-3D and 4A-4B. Further, exhaust flow through the firstand/or second scroll may be adjusted based on engine operatingconditions, such as engine speed and load, and/or desired boost pressureand torque. For example, the position of the valve 140 may be adjustedsuch the boost pressure (i.e. compressor outlet pressure) may besufficient to meet, but not to exceed, a desired boost pressure. In oneexample, if a measured boost pressure is higher than the desired boostpressure, the valve may be adjusted to increase an amount of exhaust gasflow that bypasses the turbine. In other words, the exhaust gas flow maybe directed to point 106 downstream of the turbine. As a result, theremay be a reduction in the rotational speed of the turbine andcompressor, thereby reducing boost pressure. On the other hand, if theboost pressure is lower than the desired boost pressure, the valve 140may be adjusted to decrease the amount of exhaust gas flow bypassing theturbine by providing a metered amount of opening to the wastegatepassage. Consequently, there may be an increase in the rotational speedof the turbine and compressor, thereby increasing boost pressure. Inanother example, if the turbine speed exceeds a pre-determined thresholdspeed, the valve may be adjusted to decrease the amount of exhaust gasto the turbine in order to reduce damage to the turbocharger.

As shown in FIG. 3A, an example first position of valve 140 is shown,wherein valve 140 may adjusted to be closed such that substantially allexhaust flow within the first scroll 100 may be substantially containedwithin the first scroll 100 and may be passed to turbine 92. Further,substantially all exhaust flow within second scroll 102 may besubstantially contained within second scroll 102 and may be passed toturbine 92. Additionally, the first position of valve 140 may alsoreduce or prevent exhaust flow from entering wastegate passage 104. Inthis way, adjusting the valve to the first position may increase theamount of exhaust flow to the turbine by preventing exhaust fluidcommunication between the first and second scrolls, and from the firstand second scrolls to the wastegate passage. Thus, in the firstposition, the valve may be completely closed to each of the firstscroll, second scroll, and the wastegate passage such that a vastmajority or nearly all exhaust gas flow in the first scroll 100 and inthe second scroll 102 may be separately and independently delivered toturbine 92. Further, no exhaust gas flow may bypass the turbine viawastegate passage 104. In one example, the valve 140 may be in the firstposition, or a position substantially similar to the first position,during a condition when one or more of turbine speed is less than athreshold turbine speed, boost pressure is less than a desired boostpressure, engine load is greater than a threshold load, torque demand isincreasing, and engine speed is less than a threshold engine speed.

Herein, the aforementioned threshold turbine speed may be a speed at orabove which mechanical damage on the turbine may occur, for example. Inanother example, the threshold load may be an engine load above which itmay be considered a high engine load condition, such as when the vehicleis towing a trailer or hill-climbing. In yet another example, thethreshold engine speed may be a speed at or above which excessive engineexhaust backpressure may occur in a dual scroll turbocharger system. Inother examples, the threshold load, threshold turbine speed, and/orthreshold engine speed may be based on other engine operatingconditions.

In another example, as illustrated in FIG. 3B, an example secondposition of valve 140 is provided, wherein valve 140 may be opened ametered amount to each of the first and second scrolls, and completelyopened to the wastegate passage. As such, valve 140 in the secondposition may enable partial communication of exhaust flow between thefirst and second scrolls, and full communication of exhaust flow frombetween each of the first and second scrolls and to the wastegatepassage. In other words, valve 140 may be opened the metered amount toeach of the first and second scrolls such that an amount of exhaust gasflow at an interface between each of the first scroll 100 and secondscroll 102 may exit the first scroll 100 and second scroll 102,respectively, and bypass turbine 92 via wastegate passage 104. Further,in this example, valve 140 in the second position may reduce exhaustflow communication and conveyance between the first scroll 100 and thesecond scroll 102 since the metered amount of opening of valve 140 maybe limited.

In one example, valve 140 may be in the second position, or a positionsubstantially similar to the second position, when one or more ofturbine speed is greater than the threshold turbine speed, boostpressure is greater than the desired boost pressure, engine load is lessthan the threshold load, demanded torque is decreasing, and engine speedis less than the threshold engine speed. In another example, the meteredamount of opening of valve 140 may be based on engine speed, engineload, and/or demanded torque. As such, in an example, the metered amountof opening of valve 140 to each of the first and second scrolls mayincrease as engine load or demanded torque decreases. In anotherexample, the metered amount of opening of valve 140 to each of the firstand second scrolls may increase as engine speed increases. In this way,valve 140 in the second position may enable a desired amount of exhaustflow to exit each of the first and second scrolls to enter the wastegatepassage 104 and bypass turbine 92 responsive to one or more engineoperating conditions.

Now turning to FIG. 3C, an example third position of valve 140 is shown,wherein valve 140 may be adjusted to be substantially opened to each ofthe first scroll 100 and second scroll 102, and opened a prescribedamount to wastegate passage 104. Moreover, a space having a volumeformed at an area between and adjacent to each of the first scroll andsecond scroll may be present when the valve is in the third position. Assuch, the valve in the third position may allow exhaust gas flow in eachof the first scroll 100 and second scroll 102 to “blow down” into theaforementioned space having a larger volume as compared to a volume ofspace in each of the first scroll and second scroll when the valve isclosed to each of the first scroll and second scroll, such as the firstposition. Consequently, valve 140 in the third position may allowconsiderable exhaust flow communication and conveyance between the firstscroll 100 and the second scroll 102. Concomitantly, a portion ofexhaust gas flow may escape through the prescribed amount of opening ofvalve 140 to wastegate passage 104. Thus, there may be a reduction inexhaust gas flow to the turbine 92. In one example, the valve 140 may bein the third position to allow the portion of exhaust gas flow to bypassthe turbine to limit boost pressure and/or to maintain or reduce a speedof a turbine below a threshold turbine speed.

In one embodiment, the prescribed amount of opening of valve 140 may bebased on engine operating conditions, such as engine speed, engine load,and/or demanded torque. For example, valve 140 may be in the thirdposition when the turbine speed is greater than the threshold turbinespeed. In another example, the valve may be in the third position duringa condition when one or more of boost pressure is greater than thedesired boost pressure, engine load is less than the threshold load,demanded torque is decreasing, and engine speed is greater than thethreshold engine speed. In yet another example, the prescribed amount ofopening of valve 140 to the wastegate passage 104 may increase as engineload or demanded torque decreases. In some cases, the prescribed amountof opening of valve 140 to wastegate passage 104 may increase as enginespeed decreases. In this way, valve 140 may be movable to the thirdposition to reduce boost pressure responsive to certain engine operatingconditions in order to mitigate exhaust manifold backpressure.

FIG. 3D illustrates an example fourth position of valve 140, whereinvalve 140 is substantially or completely opened to each of the firstscroll 100 and second scroll 102. In addition, valve 140 may be closedto the wastegate passage 104, such that no exhaust gas flow may exiteach of the first and second scrolls to wastegate passage 104.Consequently, valve 140 in the fourth position may allow considerableexhaust flow communication and conveyance between the first scroll 100and the second scroll 102.

Moreover, similar to the third position, a space having a volume formedat an interface between and/or an area adjacent to each of the firstscroll and second scroll when the valve is in the fourth position mayallow exhaust gas flow in the first scroll 100 and second scroll 102 to“blow down” into said space having a larger volume as compared to thevolume in each individual scroll and when the valve is closed to each ofthe first scroll and second scroll. In this way, valve 140 in the fourthposition may allow full exhaust flow communication and conveyancebetween first scroll 100 and second scroll 102, such that all exhaustflow passes through the turbine to increase boost pressure.Consequently, the fourth position may reduce exhaust backpressure, whileincreasing exhaust gas flow and energy to the turbine to increase boostpressure more rapidly.

In one example, the valve 140 may be in the fourth position, or aposition substantially similar to the fourth position, during acondition when one or more of turbine speed is less than a thresholdturbine speed, boost pressure is less than a desired boost pressure,engine load is greater than a threshold load, torque demand isincreasing, and engine speed is greater than a threshold engine speed.Said another way, the aforementioned valve configuration may provide anamount of boost pressure to achieve the desired boost pressure whilereducing exhaust manifold backpressure during high engine speeds.Although not shown, other additional and/or alternative positions, orstates, or ranges are possible in accordance with the presentdisclosure.

Turning now to FIGS. 4A-4D, sectional views of a second example branchcommunication and wastegate valve in four example positions or statesare shown. In one embodiment, a first passage, or first scroll 100, maybe positioned at a spaced distance adjacent to a second passage, orsecond scroll 102, as viewed from the plane of the paper. In oneembodiment, valve 140 may be adjusted, or movable, in a continuousmanner through selected positions, ranges, and/or states such thatexhaust gas flow through the first and second scrolls, and to thewastegate passage, may be adjusted based on engine operating conditionsand desired boost and torque, for example. As illustrated in FIGS.4A-4D, in one embodiment, valve 140 may comprise a spool valve. In thisembodiment, valve 140 may include a movable element 143 configured tomove along an axis 149 to provide selective fluidic communication andconveyance between one or more combinations of first scroll 100, secondscroll 102, and wastegate passage 104 to point 106 (depicted above inFIGS. 1-2) downstream from turbine 92.

In one embodiment, the aforementioned example positions shown inreference to FIGS. 4A-4D may be substantially the same as the examplepositions illustrated in FIGS. 3A-3D, such that adjustments to aposition of a valve, such as valve 140, may control exhaust gas flow inone or more of the first scroll, second scroll, and the wastegatepassage.

For example, as shown in FIG. 4A, a first position of valve 140 having aspool configuration may be substantially similar to the first positionof valve 140 having a cylindrical configuration described in FIG. 3A. Assuch, valve 140 may be closed such that substantially all exhaust flowwithin first scroll 100 may be substantially contained within the firstscroll 100 and may be passed to turbine 92. Similarly, substantially allexhaust flow within second scroll 102 may be substantially containedwithin second scroll 102 and may be passed to turbine 92, as shown inreference to FIGS. 1-2. Moreover, no exhaust gas flow may bypass theturbine through wastegate passage 104. Similar to valve 140 described inFIG. 3A, valve 140 having the spool configuration may be in the firstposition, or a position substantially similar to the first position,during a condition when one or more of turbine speed is less than thethreshold turbine speed, boost pressure is less than the desired boostpressure, engine load is greater than the threshold load, torque demandis increasing, and engine speed is less than the threshold engine speed.In this way, adjustment to valve 140 to the first position increases anamount of exhaust gas flow to the turbine, thereby increasing boostpressure.

In another example, as illustrated in FIG. 4B, a second position ofvalve 140 having the spool configuration is shown, which may besubstantially similar to the second position described in FIG. 3B. Inparticular, valve 140 having the spool configuration may be opened ametered amount to each of the first and second scrolls, and openedcompletely to wastegate passage 104. As such, valve 140 in the secondposition may enable partial communication of exhaust flow between thefirst and second scrolls, and full fluid communication of exhaust flowfrom between each of the first and second scrolls and to the wastegatepassage. Thus, a portion of exhaust gas flow at an interface of each ofthe first scroll 100 and second scroll 102 may exit the first scroll 100and second scroll 102, respectively, and bypass turbine 92 via wastegatepassage 104. In this way, adjustment to valve 140 to the second positionmay decrease an amount of exhaust gas flow to the turbine, therebylimiting or lowering boost pressure.

In one example, valve 140 having the spool configuration may be in thesecond position, or a position substantially similar to the secondposition, when one or more of turbine speed is greater than thethreshold turbine speed, boost pressure is greater than the desiredboost pressure, engine load is less than the threshold load, demandedtorque is decreasing, and/or engine speed is less than the thresholdengine speed. Similar to the valve illustrated in FIG. 3B, the meteredamount of opening of valve 140 having the spool configuration may bebased on engine speed, engine load, and/or demanded torque. For example,the metered amount of opening of valve 140 to each of the first andsecond scrolls may increase as engine load or demanded torque decreases.In another example, the metered amount of opening of valve 140 to eachof the first and second scrolls may increase as engine speed increases.

Now turning to FIG. 4C, a third position of valve 140 having the spoolconfiguration is shown, which may be substantially similar to the thirdposition described in FIG. 3C. In one example, in the third position,valve 140 may be opened completely to each of the first scroll 100 andsecond scroll 102, and opened a prescribed amount to wastegate passage104. As a result, valve 140 in the third position may allow substantialexhaust flow communication and conveyance between the first scroll 100and the second scroll 102. Concomitantly, a portion of exhaust gas flowmay escape through the prescribed amount of opening and into wastegatepassage 104. Thus, there may be a reduction in exhaust gas flow to theturbine 92. In this way, adjustment of valve 140 to the third positionmay limit or lower boost pressure.

In an example, the valve may be in the third position during a conditionwhen one or more of turbine speed is greater than the threshold turbinespeed, boost pressure is greater than the desired boost pressure, engineload is less than the threshold load, demanded torque is decreasing,and/or engine speed is greater than the threshold engine speed. Similarto the third position of FIG. 3C, the prescribed amount of opening ofvalve 140 shown in FIG. 4C may be based on engine operating conditions,such as engine speed, engine load, and/or demanded torque. In yetanother example, the prescribed amount of opening of valve 140 towastegate passage 104 may increase as engine load or demanded torquedecreases. In some cases, the prescribed amount of opening of valve 140to wastegate passage 104 may increase as engine speed decreases. In thisway, valve 140 may be movable to the third position to reduce boostpressure responsive to certain engine operating conditions in order tomitigate exhaust manifold backpressure during high engine speeds.

Now turning to FIG. 4D, a fourth position of valve 140 having the spoolconfiguration is shown, which may be substantially similar to the fourthposition described in FIG. 3D. In one example, valve 140 issubstantially or completely opened to each of the first scroll 100 andsecond scroll 102, and closed to wastegate passage 104. As a result, inthe fourth position, valve 140 may allow full exhaust flow communicationand conveyance between first scroll 100 and second scroll 102 such thatsubstantially all exhaust flow within each scroll passes through theturbine to increase boost pressure. In this way, adjustment to valve 140to the fourth position may increase an amount of exhaust gas flow to theturbine, thereby increasing boost pressure.

In one example, the valve 140 may be in the fourth position, or aposition substantially similar to the fourth position, during acondition when one or more of turbine speed is less than a thresholdturbine speed, boost pressure is less than a desired boost pressure,engine load is greater than a threshold load, torque demand isincreasing, and/or engine speed is greater than a threshold enginespeed. Said another way, in another example, the fourth valve positionmay provide an amount of boost pressure to achieve the desired or targetboost pressure while reducing exhaust manifold backpressure during highengine speeds. Although not shown, other positions, states, or rangesare possible in accordance with the present disclosure.

Thus, in one embodiment, a dual scroll turbocharger system may beprovided, comprising a first scroll, a second scroll, fluidicallyseparated from the first scroll via a dividing wall, a passagepositioned within the dividing wall fluidically bridging the firstscroll and the second scroll, and a valve positioned within the passageand movable between selected positions, a set of the selected positionsproviding fluid communication between the first scroll and the secondscroll, and a second set of the selected positions providing fluidcommunication between one or both of the first and second scrolls and apoint downstream from a turbine.

In one example, the valve may be positionable in a continuous mannerthrough the selected positions, the selected positions including: afirst position wherein the valve may be closed to each of the first andsecond scrolls, and closed to the point downstream from the turbine; asecond position wherein the valve may be opened a metered amount to eachof the first and second scrolls, and opened to the point downstream fromthe turbine; a third position wherein the valve may be opened completelyto each of the first and second scrolls, and opened a prescribed amountto the point downstream from the turbine; and a fourth position whereinthe valve may be opened completely to each of the first and secondscrolls, and closed to the point downstream from the turbine.

Further, in an example, the valve may be integrated into a cylinderhead. In other example, the valve may be integrated in a turbocharger oran exhaust manifold of an engine configured to use the turbochargersystem. In one embodiment, the valve may include a valve body, whereinthe valve includes one or more external surfaces disposed to allow heatto be removed from the valve body. The valve may also include anattachment mechanism, such as fasteners and/or a sealing arrangement forfluidic coupling with the engine.

FIG. 5 is a flow diagram illustrating an example routine 500 foradjusting one or more movable obstructions that are adjustable orpositionable, such as valve 140 shown in FIGS. 1-4, to provide multiplepositions of directing exhaust gas to pass from the first turbine inletscroll (e.g., first scroll 100) and/or from the second turbine inletscroll (e.g., second scroll 102) to a turbine (e.g., turbine 92) and/orto a wastegate (e.g., wastegate passage 104). Specifically, a positionof the valve may be adjusted based on one or more engine operatingconditions and/or desired or demanded engine operations. For example, aposition of the valve may be responsive to an engine speed and load, anda demanded torque requested by an operator of a vehicle. Instructionsfor carrying out routine 500 may be stored in a memory of a controller,such as controller 12 shown in FIGS. 1-2.

At 502, the routine includes estimating and/or measuring engineoperating conditions such as engine speed, load, boost, MAP, demandedboost pressure, etc. At 504, it may be determined if a speed of aturbine, such as turbine 92, for example, is below a pre-determinedthreshold speed. In one example, the threshold turbine speed may be aspeed at which the turbine output may reduce engine performance and/ordamage the turbocharger or other engine components. In another example,a speed sensor, such as speed sensor 97, may measure the speed of theturbine. Alternatively, the speed of the turbine may be estimated basedone or more engine operating conditions. In this way, if a turbine speedexceeds the pre-determined threshold speed, the valve, e.g., valve 140,may be adjusted to reduce damage to the turbocharger and/or increaseengine performance. In another embodiment, other engine operatingcondition(s) may be compared and confirmed to a corresponding thresholdvalue in place of comparing a turbine speed to a threshold turbinespeed.

If it is confirmed that the speed of the turbine is less than thethreshold turbine speed at 504, the routine continues to 506, where itis confirmed if a measured boost pressure is above a target or desiredboost pressure. In another example, at 506, it may be additionally oralternatively be confirmed if engine load is less than a thresholdengine load, wherein the threshold load may be an engine load at orabove which high engine load may be present, such as duringhill-climbing or towing, for example. In other words, the thresholdengine load may be a condition above which high engine load (torque) isdemanded, wherein the high engine load may be based on various engineoperating conditions. In yet another example, at 506, it mayadditionally or alternatively be confirmed if demanded torque isdecreasing. If the measured boost pressure is below the desired boostpressure, the engine load is greater than the threshold load, and/ordemanded torque is increasing, the routine may adjust the valve toincrease an amount of exhaust gas to the turbine at 508. In other words,the routine may increase the amount of exhaust gas flow to the turbinein order to increase the measured boost pressure and/or engine torque tothe desired boost pressure and/or engine torque, respectively.

Adjusting the valve to increase the amount of exhaust to the turbine mayinclude adjusting the valve to one of the first position and the fourthposition, as described above in FIGS. 3A and 3D, and 4A and 4D. As oneexample, the adjusting of the valve to increase the amount of exhaustgas flow to the turbine may be further determined by an engine speed at510. As such, routine 500 may confirm if the engine speed is less than apre-determined threshold engine speed. In one example, the thresholdengine speed may be a speed or range of speeds at which increasedbackpressure in the exhaust manifold may occur. In other embodiments,the routine may confirm if one or more additional or alternative engineoperating conditions, such as demanded torque or engine load, is greaterthan a corresponding pre-determined threshold. For example, the routinemay confirm if increasing engine load (torque) is demanded and/or ifengine load is greater than a threshold load in tandem with, before, orafter determining if engine speed is greater than the threshold enginespeed at 510.

In one embodiment, if the engine speed less than the threshold enginespeed, routine may proceed to 512, and may adjust the valve to the firstposition, as described above with reference to FIGS. 3A and 4A. Inanother example, the valve may be adjusted to a position substantiallysimilar to the first position, such that substantially all exhaust gasflow within each of the first scroll and the second scroll are directedto the turbine. Further, the valve may be simultaneously closed to anyother scroll(s) and to the wastegate passage, e.g., wastegate passage104. In this way, considerably all exhaust gas flow within each of thefirst and second scroll may drive the turbine in order to provideincreased boost pressure to achieve the desired boost pressure whenengine speed is less than the threshold engine speed (e.g., during lowengine speed).

However, if it is confirmed at 510 that the engine speed (or otheroperating condition) is above the threshold engine speed (or otherpre-determined threshold level), the routine may adjust the valve to thefourth position, for example, at 514, as described above with referenceto FIGS. 3D and 4D. In another example, the valve may be adjusted to aposition substantially similar to the fourth position, such that thevalve may be fully opened to each of the first and second scrolls, andclosed to the wastegate passage. In other words, a portion of exhaustgas flow in the first scroll 100 may mix and combine with a portion ofexhaust gas flow in the second scroll 102. However, no amount of exhaustgas from either the first scroll 100 or second scroll 102 may exiteither scroll via wastegate passage 104. Moreover, a space having avolume formed between an area adjacent to the first scroll and secondscroll when the valve is in the fourth position may allow the portion ofexhaust gas in the first scroll 100 and second scroll 102 to “blow down”into the larger volume space (as compared to the volume in eachindividual scroll when the valve is closed to each of the first scrolland second scroll). In this way, the valve in the fourth position, or aposition substantially similar, may direct considerably all exhaust gasflow in the first and second scroll to drive the turbine. Thus, theaforementioned fourth valve position of valve 140 may provide increasedboost pressure to achieve the desired boost pressure while reducingexhaust manifold backpressure when engine speed is greater than thethreshold engine speed (e.g., during high engine speed).

On the other hand, if it is confirmed at 504 that the turbine speed isgreater than the threshold turbine speed, or if it is confirmed at 506that the measured boost pressure is greater than the desired or targetboost pressure, the engine load is less than the threshold load, and/orthat torque demand is decreasing, the routine may continue to 516,wherein the valve may be adjusted to decrease an amount or volume ofexhaust gas flow to the turbine. In this way, in one example, adjustingthe valve to decrease an amount of exhaust to the turbine may reducepotential damage to the turbocharger when turbine speed exceeds thethreshold speed. In another example, adjusting the valve to decrease theamount of exhaust to the turbine when a boost pressure exceeds thedesired boost pressure, when engine load is less than the thresholdload, and/or when torque demand is decreasing.

Adjusting the valve to decrease the amount of exhaust to the turbine mayinclude adjusting the valve to one of the second position and the thirdposition, as described above with reference to FIGS. 3B and 3C, and 4Band 4C. As one example, the adjusting of the valve to decrease theamount of exhaust gas flow to the turbine may be further determined byengine speed at 518.

As such, at 518, the routine may confirm if an engine speed is greaterthan a second threshold engine speed. Similar to at 510, the secondthreshold engine speed may be a speed or range of speeds at which excessbackpressure in the exhaust manifold may occur. In other words, thesecond threshold engine speed at 518 may be the same as the firstpre-determined threshold speed at 510. In another embodiment, theroutine may additionally or alternatively confirm if one or more otheroperating condition(s) are above one or more correspondingpre-determined threshold levels if these conditions were not confirmedat a preceding step. As an example, the routine may confirm if demandedtorque and/or engine load are greater than corresponding pre-determinedthresholds.

At 518, if the engine speed is less than the threshold engine speed,routine 500 may proceed to 522, wherein the valve, e.g., valve 140, maybe adjusted to the second position, or a position substantially similarto the second position, as described above in reference to FIGS. 3B and4B. The second position may include the valve being opened a meteredamount to each of the first and second scrolls, and completely opened tothe wastegate passage. As such, adjusting the valve to the secondposition may enable partial communication of exhaust between the firstand second scrolls and full communication of exhaust from between thefirst and second scrolls and to the wastegate passage. In this way,adjusting the valve to the second position may maintain or reduce boostpressure during a low engine speed, a low engine load, and/or low ordecreasing demanded torque.

Further, the metered amount of opening of valve 140 may be adjustedbased on various engine operating conditions. For example, the meteredamount of opening may decrease with increasing engine torque demandsand/or engine loads. In another example, the metered amount of openingof valve 140 may increase as engine speed increases.

However, if it is confirmed at 518 that the engine speed (or otheroperating condition(s)) is greater than threshold engine speed, theroutine may adjust the valve to the third position at 520, or a positionsubstantially similar to the third position, as described above withreference to FIGS. 3C and 4C. As such, valve 140 may be openedcompletely to each of the first scroll 100 and second scroll 102, andopened a prescribed amount to wastegate passage 104 to decrease theamount of exhaust flow to the turbine. In other words, there may be fullcommunication of exhaust between the first and second scrolls andpartial communication of exhaust from between the first and secondscrolls and to the wastegate passage. In this way, the aforementionedvalve configuration may provide a desired boost pressure to meet asteady or decreasing demand for torque while reducing exhaust manifoldbackpressure during high engine speeds. The metered amount of opening ofvalve 140 may be adjusted based on various engine operating conditions.For example, the metered amount of opening may decrease with increasingengine torque demands and/or engine loads.

Thus, in some embodiments, routine 500 may allow substantially noexhaust gas to bypass the turbine (e.g., valve is adjusted to the firstposition, as described in FIGS. 3A and 4A, and/or fourth position, asshown in FIGS. 3D and 4D), and/or allow a portion of exhaust gas tobypass the turbine (e.g., valve is adjusted to the second position, asdescribed in FIGS. 3B and 4B, and/or third position, as shown in FIGS.3C and 4C). Thus, by adjusting a combination branch communication andwastegate valve, e.g., valve 140, an amount of fluidic communicationamong the first scroll 100, the second scroll 102, and the wastegatepassage 104 may also be adjusted by controller 12 based on variousengine operating conditions, such as engine load, engine speed, desiredboost, and/or demanded torque. Consequently, an efficiency of theturbine (and turbocharger) and an amount of backpressure in the exhaustmanifold may be controlled to achieve desired boost level(s) and enginetorque. In other embodiments, adjusting the valve may provide theefficiency of the turbocharger and backpressure to be withinpredetermined range(s). The efficiency may be determined, for example,by monitoring the intake air pressure, which may be measured, forexample, with pressure sensor 132. Other engine sensors and/or sensorsnot currently described herein, and/or sensors that may not be used incurrent engine designs may additionally or alternatively be used. Forexample, an exhaust gas pulse profile may be measured directly and/ordetermined by one or more sensor readings, or other measures andinferred or calculated by a controller, e.g., controller 12.

FIG. 6 includes graph 600 illustrating example adjustments to a positionof a valve in response to engine operating conditions, including one ofan engine load, engine speed, demanded boost pressure, and turbinespeed. Specifically, graph 600 shows adjustments to valve position atplot 602, changes in engine load at plot 604, changes in engine speed atplot 606, changes in desired boost pressure at dotted plot 610, measuredboost pressure at plot 608, changes in turbine speed at plot 612, andchanges in amount of exhaust to turbine at plot 614. The valve discussedin FIG. 6 may be a combined branch communication and wastegate valve, asdescribed above with reference to FIGS. 1-5. For example, the valve ofFIG. 6 may be one of the valves depicted in FIGS. 3 and 4. Further, aposition of the valve in this example may be one of the first position(denoted by “1”), second position (denoted by “2”), third position(denoted by “3”), and fourth position (denoted by “4”), as discussedabove in reference to FIGS. 3A-4D. Time is plotted along the x-axis, andtime increases from the left of the x-axis to the right. Further, athreshold engine load (e.g., T1) is represented by line 624, a thresholdengine speed (e.g., T2) is shown by line 626, while a threshold turbinespeed (e.g., T3) is represented at line 622.

Prior to time t1, the engine is off such that no combustion isoccurring. At time t1, the engine is activated and may begin combusting.Between time t1 and time t2, the vehicle may be traveling along a roadwith a slight incline. Therefore, the engine load is graduallyincreasing, but remains below the threshold engine load T1 (e.g., line624). Similarly, engine speed is steadily increasing, but still remainsbelow the threshold engine speed T2 (e.g., line 626). In response to theaforementioned engine operating conditions, the valve may be adjusted tothe second position (or a position substantially similar to the secondposition) at time t1 and maintained in the second position between timet1 and time t2. For example, in the second position, the valve may beopened a metered amount to each of the first and second scrolls of theturbine, and opened completely to the wastegate passage. Thus, a meteredamount of exhaust gas from each of the scrolls enters the wastegatepassage, thereby bypassing the turbine and reducing an amount of exhaustgas to the turbine as compared to a condition when the valve iscompletely closed to the wastegate passage. Since engine load is notabove the threshold engine load between time t1 and time t2, themeasured boost pressure (e.g., line 610) may reach the desired boostpressure (e.g., line 608) such that the measured and desired boostpressure are substantially the same. Further, turbine speed remains lessthan the threshold turbine speed T3 (e.g., line 622) because an amountof exhaust gas may bypass the turbine via the wastegate passage throughthe metered amount of opening.

At time t2, the vehicle may be traveling on a steeper incline road. Assuch, the engine load is increasing to meet and/or exceed the thresholdengine load, T1, above which the vehicle operator may demand increasedboost pressure at time t2. Further, the engine speed is increasing, butdoes not reach the threshold engine speed, T2, at time t2. Thus, thevalve may be adjusted to the first position, or a position substantiallysimilar to the first position, wherein the valve is closed to each ofthe first and second scrolls, and to the wastegate passage. In this way,between time t2 and time t3, substantially all exhaust gas from each ofthe first and second scrolls are directed to the turbine, and may notescape through the wastegate passage. Therefore, the desired boostpressure and measured boost pressure increase in response to increasedengine load. In this particular example, the measured boost pressure maynot meet the desired boost pressure between time t2 and time t3.

At time t3, the engine speed may reach and/or exceed the thresholdengine speed, T2. As discussed above, the threshold engine speed may bea speed at or above which excessive engine exhaust backpressure mayoccur in a dual scroll turbocharger system. The vehicle may continue tohill climb between time t3 and time t4, and both engine speed and engineload are above their respective thresholds, T1 and T2. Concomitantly,turbine speed may also be increasing, but remain below the thresholdturbine speed, T3. In response, the valve may be adjusted to the fourthposition, or a position substantially similar to the fourth position,wherein the valve is opened to each of the first and second scrolls, andclosed to the wastegate passage. Thus, as discussed above, substantiallyall exhaust gas from each of the first and second scrolls are directedto the turbine, and may not escape through the wastegate passage.Further, a space having a volume may form at an area adjacent to aninterface of each of the first scroll, second scroll, and wastegatepassage, such that an amount of exhaust gas may “blow down” into saidspace. In this way, there may be a reduction in backpressure and pumpingwork while increasing an amount of exhaust gas to the turbine toincrease measured boost pressure to meet the desired boost pressure.Consequently, by time t4, the amount of exhaust gas flow to the turbineresults in the measured boost pressure being substantially similar tothe desired boost pressure.

At time t4, the vehicle may not be hill climbing, but instead, may betraveling on a road having little incline. In other examples, thevehicle may be moving downhill. In the aforementioned examples, theengine load may decrease below the threshold engine load. However,engine speed may still be above the threshold engine speed.Consequently, the desired boost pressure may decrease in response todeclining engine load, and the valve may be adjusted to the thirdposition, or a position substantially similar, at time t4. In the thirdposition, the valve is opened completely to each of the first and secondscrolls and opened a prescribed amount to the wastegate. As a result, anamount of exhaust gas may bypass the turbine, and enter the wastegatepassage to a point downstream of the turbine. Similar to the fourthposition, the third position may also provide a space having a volumeformed at an area adjacent to an interface of each of the first andsecond scrolls, and the wastegate passage. Thus, when engine load, ordemanded torque, is steady or decreasing as shown, and engine speed isgreater than the threshold engine speed T2, the valve may be adjusted tothe third position to reduce backpressure and pumping work. Further, theturbine speed steadily declines.

At time t5, the vehicle may continue moving downhill or on a road withlittle incline, and the engine speed decreases below the thresholdengine speed, T2. Further, the engine load continues to steadilydecrease, thereby reducing desired boost pressure between time t5 andtime t6. In this example, the desired boost pressure and measured boostpressure is substantially the same between time t5 and time t6. Sinceengine load and boost pressure are not increasing, the valve may beadjusted to the second position to decrease an amount of exhaust flow tothe turbine, wherein the valve is opened a metered amount to each of thefirst and second scrolls, and opened to the wastegate passage. In thisway, an amount of exhaust gas in each of the first and second scrollsmay be diverted away from the turbine to the point downstream of theturbine via the wastegate passage between time t5 and time t6. Since theamount of exhaust flow to the turbine is decreasing, the turbine speedis also decreasing between time t5 and time t6.

Between time t6 and t7, the vehicle may again begin to travel uphill,for example. In another example, the vehicle may be towing a trailer. Asshown in this example, the engine load is increasing, but has not yetreached the threshold engine load between time t6 and t7. Although thethreshold engine load has not been met by the measured engine load, thevalve may be adjusted to the first position, or a position substantiallysimilar to the first position, in order to drive an amount of exhaustflow to the turbine to meet an increase in demanded torque and boostpressure.

At time t7, the engine load reaches and/or exceeds the threshold engineload, T1, and the desired or demanded boost pressure is increased inresponse to the higher engine load. Further, the engine speed betweentime t6 and time t7 also increases, but has not yet reached thethreshold engine speed, T2, at time t7. In response to the engine loadexceeding the threshold engine load and the engine speed being less thanthe threshold engine speed, the valve may be adjusted to or remain inthe first position, or a position substantially similar to the firstposition, to direct substantially all exhaust gas flow within the firstand second scrolls to the turbine, thereby increasing turbine speed andmeasured boost pressure. Between time t7 and time t8, the desired boostpressure is greater than the measured boost pressure. However, themeasured boost pressure is steadily increasing to meet the desired boostpressure at time t8.

At time t8, the engine speed is reaching and/or exceeding the thresholdengine speed, T2, as engine load continues to remain above the thresholdengine load. In response, the valve may be adjusted to the fourthposition, or a position substantially similar to the fourth position,such that substantially all exhaust gas flow within the first and secondscrolls are directed to the turbine to increase boost pressure and maynot escape through the wastegate passage between times t8 and t9.Further, the aforementioned space having a volume may form at an areaadjacent to an interface of each of the first scroll, second scroll, andwastegate passage, such that an amount of exhaust gas may “blow down”into said space. In this way, there may be a reduction in backpressureand pumping work while increasing an amount of exhaust gas to theturbine to increase measured boost pressure to meet the desired boostpressure. Consequently, the amount of exhaust gas flow to the turbineresults in the measured boost pressure being substantially similar tothe desired boost pressure. In addition, turbine speed continues toincrease as exhaust flow is driving the turbine.

At time t9, the turbine speed is increasing to meet and/or exceed thethreshold turbine speed. As mentioned above, the threshold turbine speedmay be a speed at or above which mechanical damage on the turbine mayoccur, for example. In response to the turbine speed being greater thanthe threshold turbine speed, the valve may be adjusted to the thirdposition in order to reduce the speed of the turbine despite engine loadand/or engine speed being greater than their respective thresholds, T1and T2. In the third position, the valve is opened completely to each ofthe first and second scrolls and opened a prescribed amount to thewastegate. As a result, an amount of exhaust gas may bypass the turbine,and enter the wastegate passage to the point downstream of the turbinebetween time t9 and time t10. As discussed above, the third position mayalso provide said space having a volume formed at an area adjacent to aninterface of each of the first and second scrolls, and the wastegatepassage. Thus, when turbine speed is above the threshold turbine speed,and engine speed is greater than the threshold engine speed T2, thevalve may be adjusted to the third position to decrease turbine speedwhile simultaneously reducing backpressure and pumping work. However,between time t9 and time t10, the desired boost pressure is greater thanthe measured boost pressure due to the amount of exhaust gas escapingthrough the turbine.

Consequently, the speed of the turbine may decline between time t9 andtime t10, resulting in the turbine speed being below the thresholdturbine speed at time t10. In addition, at time t10, the vehicle maybegin traveling on a road having little to no incline, such that engineload falls below the threshold engine load, T1, and desired boostpressure decreases. However, engine speed remains about the thresholdengine speed. In response to each of the decreasing engine load, reduceddesired boost pressure, and engine speed above the threshold enginespeed, the valve may be remain, or be adjusted to, the third position.In the third position, the valve is opened completely to each of thefirst and second scrolls and opened a prescribed amount to thewastegate. Therefore, an amount of exhaust gas may bypass the turbine,and enter the wastegate passage to a point downstream of the turbinebetween time t10 and time t11. Moreover, backpressure and pumping workmay also be reduced when the valve is in the third position and enginespeed is greater than the threshold engine speed.

At time t11, the vehicle may continue moving downhill or on a road withlittle incline (e.g., a flat road), and the engine speed decreases belowthe threshold engine speed, T2. Further, the engine load continues tosteadily decrease, thereby reducing desired boost pressure between timet11 and time t12. Since engine load, engine speed, and boost pressureare decreasing, the valve may be adjusted to the second position toreduce an amount of exhaust flow to the turbine, wherein the valve isopened a metered amount to each of the first and second scrolls, andopened to the wastegate passage. In this way, an amount of exhaust gasin each of the first and second scrolls may be diverted away from theturbine to the point downstream of the turbine via the wastegatepassage. Since the amount of exhaust flow to the turbine is decreasing,the turbine speed is also decreasing. As shown in this example, thedesired boost pressure and measured boost pressure is substantially thesame between time t11 and time t12. At time t12, a vehicle cyclecomprising all events between time t1 and time t12 ends.

The technical effect of adjusting a valve positioned in a passageconnecting a first scroll, a second scroll, and a wastegate passage tocontrol an amount of exhaust flow to the turbine is an effective andefficient control of boost pressure based on engine operatingconditions, such as engine speed, engine load, and torque demand, whilereducing backpressure and pumping work. Further, there may be areduction in cost, weight, and packaging penalties associated withincluding a single combined branch communication valve and wastegatevalve in the turbocharger and engine system, as compared to installingthese components separately. There may also be less burden on an enginecontrol and monitoring system when only a single valve is adjustable bythe aforementioned system based on engine operating conditions.

Thus, in one embodiment, a method may be provided, comprising adjustinga valve positioned in a passage connecting a first scroll and a secondscroll of a turbine to increase an amount of exhaust flow to the turbinewhen a turbine speed is less than a threshold and during a first loadcondition, and adjusting the valve to decrease the amount of exhaustflow to the turbine when turbine speed is greater than the thresholdengine speed. Moreover, the valve may be in fluid communication with awastegate passage flowing exhaust around the turbine.

In one example, the first load condition may include one or more ofboost pressure being less than a desired boost pressure, engine loadbeing greater than a threshold load, and torque demand increasing. Inanother example, adjusting the valve to increase the amount of exhaustflow to the turbine may include adjusting the valve to a first positionand not communicating exhaust between the first and second scrolls andfrom the first and second scrolls to the wastegate passage, the firstposition including the valve being completely closed to each of thefirst scroll, second scroll, and the wastegate passage, when enginespeed is less than a threshold engine speed. In yet another example,adjusting the valve to increase the amount of exhaust flow to theturbine may include adjusting the valve to a fourth position andcommunicating exhaust between the first and second scrolls but not fromthe first and second scrolls to the wastegate passage, the fourthposition including the valve being completely opened to each of thefirst scroll and second scroll, and completely closed to the wastegatepassage, when engine speed is greater than the threshold engine speed.

Further, in another embodiment, the method may also comprise adjustingthe valve to decrease the amount of exhaust flow to the turbine whenturbine speed may be less than the threshold and during a second loadcondition, the second load condition including one or more of boostpressure being greater than the desired boost pressure, engine loadbeing less than the threshold load, and decreasing torque demand.

In one example, adjusting the valve to decrease the amount of exhaustflow to the turbine may include adjusting the valve to a second positionand partially communicating exhaust between the first and second scrollsand fully communicating exhaust from between the first and secondscrolls and to the wastegate passage, the second position including thevalve being opened a metered amount to each of the first and secondscrolls, and completely opened to the wastegate passage, when the enginespeed is less than the threshold engine speed. In addition, the methodmay increase the metered amount of opening to each of the first andsecond scroll as engine speed increases.

In another example, adjusting the valve to decrease the amount ofexhaust flow to the turbine may include adjusting the valve to a thirdposition and fully communicating exhaust between the first and secondscrolls and partially communicating exhaust from between the first andsecond scrolls and to the exhaust passage, the third position includingthe valve being completely opened to each of the first and secondscroll, and opened a metered amount to the wastegate passage when theengine speed is greater than the threshold engine speed. Further, themethod may include increasing the metered amount of opening to thewastegate passage as engine speed decreases.

In some embodiments, the valve may be a cylindrical valve that rotateson a first axis perpendicular to a direction of exhaust flow througheach of the first scroll and the second scroll. In other embodiments,the valve may be a spool valve having a movable element configured tomove along a second axis to provide selective fluidic communicationbetween each of the first scroll, the second scroll, and the wastegatepassage.

In addition, in one embodiment, an engine system may be providedcomprising a first passage for fluid conveyance from a first set ofcombustion chambers to a turbine, a second passage for fluid conveyancefrom a second set of combustion chambers to the turbine, and separatedfrom the first passage by a dividing wall, a third passage for fluidconveyance from the first passage and the second passage to a locationdownstream from the turbine, a valve positioned in the dividing wall forselectively allowing fluid from one of the first and second passages toanother of the first and second passages and for selectively allowingfluid from one or both of the first and second passages to the locationdownstream from the turbine.

In one example, the valve may be integrated into one of a cylinder head,an exhaust manifold, and a turbocharger of an engine configured to use aturbocharger system. In another example, the valve may be a cylindricalvalve that rotates on a first axis perpendicular to a direction ofexhaust flow through each of the first scroll and the second passage. Inalternate examples, the valve may be a spool valve having a movableelement configured to move along a second axis to provide selectivefluid conveyance between one or more combinations of the first passage,the second passage, and the third passage.

In yet another embodiment, the valve may be positionable via a signalreceived from a controller in a continuous manner through selectedranges. As such, the valve may be closed to each of the first and secondscrolls, and closed to the point downstream from the turbine when boostpressure is less than a threshold pressure and engine speed is less thana threshold engine speed. In another example, the valve may be opened ametered amount to each of the first and second scrolls, and opened tothe point downstream from the turbine when boost pressure is greaterthan the threshold pressure and engine speed is less than the thresholdengine speed. In yet another example, the valve may be opened completelyto each of the first and second scrolls, and opened a prescribed amountto the point downstream from the turbine when boost pressure is greaterthan the threshold pressure and engine speed is greater than thethreshold engine speed. In an alternative example, the valve may beopened completely to each of the first and second scrolls, and closed tothe point downstream from the turbine when boost pressure is less thanthe threshold pressure and engine speed is greater than the thresholdengine speed.

In another representation, a method for an engine is provided,comprising allowing at least a portion of an exhaust gas to pass from afirst turbine inlet scroll to a second turbine inlet scroll and to aturbine via one or more moveable obstructions during a first condition;and allowing at least a portion of the exhaust gas to exit the firstand/or second turbine inlet scroll and to bypass the turbine to anexhaust path via the one or more movable obstructions during a secondcondition. Furthermore, during the first condition, the method includesadjusting the one or more movable obstructions to be closed to each ofthe first and second turbine inlet scrolls and closed to a wastegatepassage when engine speed is below a threshold. Alternatively, themethod includes adjusting the one or more movable obstructions to beopened completely to each of the first and second turbine inlet scrollsand closed to a wastegate passage when engine speed is above thethreshold. In another example of the aforementioned representation, thesecond condition may include adjusting the one or more movableobstructions to be opened a metered amount to each of the first andsecond turbine inlet scrolls and opened completely to the wastegatepassage when engine speed is below the threshold. On the other hand,when engine speed is above the threshold, the method may includeadjusting the one or more movable obstructions to be closed to each ofthe first and second turbine inlet scrolls and opened a prescribedamount to the wastegate passage when engine speed is above the thresholdspeed.

Further, in the representation, one or more movable obstructions may beone of a cylindrical valve and a spool valve. The one or more movableobstructions may be integrated into a cylinder head, turbocharger, or anexhaust manifold of an engine configured to use the turbocharger system.

Note that the example control and estimation routines included hereincan be used with various engine and/or vehicle system configurations.The control methods and routines disclosed herein may be stored asexecutable instructions in non-transitory memory and may be carried outby the control system including the controller in combination with thevarious sensors, actuators, and other engine hardware. The specificroutines described herein may represent one or more of any number ofprocessing strategies such as event-driven, interrupt-driven,multi-tasking, multi-threading, and the like. As such, various actions,operations, and/or functions illustrated may be performed in thesequence illustrated, in parallel, or in some cases omitted. Likewise,the order of processing is not necessarily required to achieve thefeatures and advantages of the example embodiments described herein, butis provided for ease of illustration and description. One or more of theillustrated actions, operations and/or functions may be repeatedlyperformed depending on the particular strategy being used. Further, thedescribed actions, operations and/or functions may graphically representcode to be programmed into non-transitory memory of the computerreadable storage medium in the engine control system, where thedescribed actions are carried out by executing the instructions in asystem including the various engine hardware components in combinationwith the electronic controller.

It will be appreciated that the configurations and routines disclosedherein are exemplary in nature, and that these specific embodiments arenot to be considered in a limiting sense, because numerous variationsare possible. For example, the above technology can be applied to V-6,I-4, I-6, V-12, opposed 4, and other engine types. The subject matter ofthe present disclosure includes all novel and non-obvious combinationsand sub-combinations of the various systems and configurations, andother features, functions, and/or properties disclosed herein.

The following claims particularly point out certain combinations andsub-combinations regarded as novel and non-obvious. These claims mayrefer to “an” element or “a first” element or the equivalent thereof.Such claims should be understood to include incorporation of one or moresuch elements, neither requiring nor excluding two or more suchelements. Other combinations and sub-combinations of the disclosedfeatures, functions, elements, and/or properties may be claimed throughamendment of the present claims or through presentation of new claims inthis or a related application. Such claims, whether broader, narrower,equal, or different in scope to the original claims, also are regardedas included within the subject matter of the present disclosure.

The invention claimed is:
 1. A method, comprising: adjusting a valvepositioned in a passage connecting a first scroll and a second scroll ofa turbine and connected to a wastegate passage flowing exhaust aroundthe turbine into a first position to increase an amount of exhaust flowto the turbine when a turbine speed is less than a threshold and duringa first load condition of the engine, the first position including thevalve being completely closed to each of the first scroll, the secondscroll, and the wastegate passage; adjusting the valve into a secondposition to decrease the amount of exhaust flow to the turbine whenengine speed is less than a threshold engine speed and during a secondload condition of the engine, the second position including the valvebeing partially opened to each of the first and second scrolls, andcompletely opened to the wastegate passage; and adjusting the valve fromthe first position to a third position, without passing through thesecond position, when engine speed is greater than the threshold enginespeed and during a third load condition of the engine, the thirdposition including the valve being completely opened to each of thefirst scroll and the second scroll, and completely closed to thewastegate passage.
 2. The method of claim 1, wherein the valvepositioned within a dividing wall separating the first scroll and thesecond scroll.
 3. The method of claim 1, wherein the first loadcondition includes one or more of boost pressure being less than adesired boost pressure, engine load being more than a threshold load,and increasing torque demand.
 4. The method of claim 3, wherein thesecond load condition includes one or more of boost pressure beinggreater than the desired boost pressure, engine load being less than thethreshold load, and decreasing torque demand, and wherein the third loadcondition includes engine load being greater than the threshold load. 5.The method of claim 1, wherein adjusting the valve into the firstposition includes not communicating exhaust between the first and secondscrolls and from the first and second scrolls to the wastegate passage,and wherein adjusting the valve from the first position to the thirdposition includes increasing communication of exhaust between the firstscroll and second scroll and not communicating exhaust from the firstand second scrolls to the wastegate passage.
 6. The method of claim 1,wherein adjusting the valve into the second position includes partiallycommunicating exhaust between the first and second scrolls and fullycommunicating exhaust from between the first and second scrolls and tothe wastegate passage, and only a portion of exhaust gas less than anamount of exhaust gas flowing between the first and second scrolls whenthe valve is in the third position is flowed between the first andsecond scrolls.
 7. The method of claim 6, further comprising increasingexhaust gas flow to each of the first and second scrolls as engine speedincreases.
 8. The method of claim 1, further comprising adjusting thevalve to a fourth position and fully communicating exhaust between thefirst and second scrolls and partially communicating exhaust frombetween the first and second scrolls and to the wastegate passage, thefourth position including the valve being completely opened to each ofthe first and second scrolls, and partially opened to the wastegatepassage, when engine speed is greater than the threshold engine speedand during one or more of the first load condition and turbine speedgreater than the threshold.
 9. The method of claim 8, further comprisingincreasing exhaust gas flow to the wastegate passage as engine speeddecreases.
 10. The method of claim 1, wherein the valve is a cylindricalvalve that rotates on a first axis perpendicular to a direction ofexhaust flow through each of the first scroll and the second scroll, andwherein the cylindrical valve is positioned in an area adjacent to andshares an interface with the first scroll and the second scroll.
 11. Themethod of claim 10, wherein adjusting the valve from the first positionto the third position, without passing through the second position,includes rotating the valve in a clockwise direction.
 12. A dual scrollturbocharger system, comprising: a first scroll; a second scroll,fluidically separated from the first scroll via a dividing wall arrangedbetween the first scroll and the second scroll; a passage positionedwithin the dividing wall, fluidically bridging the first scroll and thesecond scroll, and in fluidic communication with a point downstream froma turbine; a valve positioned within the passage and movable betweenselected positions; and a controller programmed to adjust the valvebetween selected positions, including: a first position wherein thevalve is closed to each of the first and second scrolls, and closed tothe point downstream from the turbine; a second position wherein thevalve is partially opened to each of the first and second scrolls, andcompletely opened to the point downstream from the turbine; and a thirdposition wherein the valve is opened completely to each of the first andsecond scrolls, and closed to the point downstream from the turbine, andwhen the valve is moved between the first and third positions, the valveis maintained closed to the point downstream from the turbine withoutpassing through the second position and opening communication betweenthe point downstream from the turbine and each of the first scroll andthe second scroll.
 13. The dual scroll turbocharger system of claim 12,wherein the valve is rotatable about an axis that is arrangedperpendicular to flow through the first scroll and the second scroll,through the selected positions, the selected positions furtherincluding: a fourth position wherein the valve is opened completely toeach of the first and second scrolls, and partially opened to the pointdownstream from the turbine.
 14. The dual scroll turbocharger system ofclaim 12, wherein the valve is integrated into one of a cylinder head, aturbocharger, and an exhaust manifold of an engine configured to use theturbocharger system, wherein the valve includes a valve body, andwherein the valve includes one or more external surfaces disposed toallow heat to be removed from the valve body.
 15. An engine systemcomprising: a first passage for fluid conveyance from a first set ofcombustion chambers to a turbine; a second passage for fluid conveyancefrom a second set of combustion chambers to the turbine, and separatedfrom the first passage by a dividing wall; a third passage for fluidconveyance from the first passage and the second passage to a locationdownstream from the turbine; a valve positioned in the dividing wall;and a controller programmed to adjust the valve between selectedpositions, including: a first position wherein the valve is closed toeach of the first and second passages, and closed to the locationdownstream from the turbine when boost pressure is less than a desiredpressure and engine speed is less than a threshold engine speed; asecond position wherein the valve is opened partially to each of thefirst and second passages, and completely opened to the locationdownstream from the turbine when boost pressure is greater than thedesired pressure and engine speed is less than the threshold enginespeed; a third position wherein the valve is opened completely to eachof the first and second passages, and partially opened to the locationdownstream from the turbine when boost pressure is greater than thedesired pressure and engine speed is greater than the threshold enginespeed; and a fourth position wherein the valve is opened completely toeach of the first and second passages, and closed to the locationdownstream from the turbine when boost pressure is less than the desiredpressure and engine speed is greater than the threshold engine speed.16. The engine system of claim 15, wherein the valve is integrated intoone of a cylinder head, an exhaust manifold, and a turbocharger of anengine configured to use a turbocharger system.
 17. The engine system ofclaim 16, wherein the valve is a cylindrical valve that rotates on afirst axis perpendicular to a direction of exhaust flow through each ofthe first passage and the second passage.
 18. The engine system of claim17, wherein the valve is rotatable about the first axis and wherein thecontroller is further configured to rotate the valve in a clockwisedirection from the first position to the fourth position without passingthrough the second and third positions.